De or het mediatheekcommissie?

The correct Dutch article is:

de mediatheekcommissie

Rule Words ending in -tie and -sie: almost always de. See the rule

How to use mediatheekcommissie

the mediatheekcommissiede mediatheekcommissie
this mediatheekcommissiedeze mediatheekcommissie
that mediatheekcommissiedie mediatheekcommissie
our mediatheekcommissieonze mediatheekcommissie
your mediatheekcommissiejouw mediatheekcommissie
every mediatheekcommissieelke mediatheekcommissie
which mediatheekcommissie?welke mediatheekcommissie?
a big mediatheekcommissie / the big mediatheekcommissieeen grote mediatheekcommissie, de grote mediatheekcommissie